Attempts have been made to heat food bodies by causing microwave energy to be absorbed by an intermediate body such as a block of ferrite which, in turn, transferred heat to the food body. However, such attempts have not been economically practical since the intermediate materials chosen, such as ferrites, have generally been large and bulky, for example, on the order of a quarter wavelength thick or thicker, and generally the ferrites available have been sintered material which cracked due to the differential temperature encountered in the ferrite.
In addition, when microwave energy is absorbed by the food body itself, the interior portion of the food body becomes overcooked compared with the surface conditions. This is particularly true for food bodies such as steaks and hamburgers where a browned surface food products preferably has a gradation of cooking extending to rare in the center.
Also, heat loss is encountered in cooking foods having juices such as meat fats, by reason of the juice which drains from the meat continuing to absorb microwave energy. This results in a reduction in the cooking rate for a given level of microwave power and a corresponding increase in cooking time as well as changes in the surface texture of the cooked food product.